1. Field of the Invention
The present invention relates to a continuously-variable-transmission control device including a V-belt type continuously variable transmission and an actuator for changing the change gear ratio of the V-belt type continuously variable transmission.
2. Description of Related Art
It is known in the art to provide a continuously-variable-transmission control device including a V-belt type continuously variable transmission and an actuator, wherein the change gear ratio of the V-belt type continuously variable transmission is automatically changed by the actuator. It is also known to provide a continuously-variable-transmission control device that compares a change gear ratio preset according to the throttle opening of the vehicle with a change gear ratio calculated from the measurement of the primary-sheave-rotation-speed sensor and the measurement of a secondary-sheave-rotation-speed sensor and that performs feedback control so that the deviation becomes zero (for example, refer to Japanese Patent No. 3,194,641).
The V-belt is worn down from long-time use to decrease in width. The decrease in the width causes the sheave to be displaced, so that the actual change gear ratio deviates from an intended change gear ratio. However, the continuously-variable-transmission control device described in Japanese Patent No. 3,194,641 performs feedback control based on a measured change gear ratio (actual change gear ratio). Accordingly, there is no problem even if the sheave is displaced with a decrease in the width of the belt.
However, such feedback control increases the processing load on the control device for controlling the drive of the actuator. In addition, it does not always provide sufficient control response and stability. Moreover, since the driver cannot recognize the wear of the V-belt, it is difficult to replace the V-belt at an appropriate time.